Process of detinning.



1* ttANZ VON KUGELGEN AND GEORGE O. SEWARD, OF

BY MESN-E ASSIGNMENTS, TO TIN TION OF NEW YORK.

PROCESS OF DETINN IN G.

Specification of Letters Patent.

Patented March 9, 1909.

Applicationfiled January 16, 1904. Serial No. 189,272.

T 0 all whom it may concern:

Be it known that we, FRANZ VON KUenL- GEN, a subject of the German Emperor, and GEORGE O. SEWARD, a citizen of the United States, both residing at Holcombs Rock, in the county of Bedford and State of Virginia, have jointly invented certain new and useful mprovements in rocesses of Detinning, of which the following is a specification.

This invention aims to economically recoverthe tin from tin scrap.

r The processes of detinnin heretofore in use are subject to the disa vanta es that they fail torecover all of the tin, and the tin which is recovered is accompanied by iron or other elements presentin the scrap which are dissolved as impurities with the tin.

The present invention secures a complete detinning, and removes the tin without attacking the iron. Itis based on the fact that dry chlorin at a suitably low temperature combines with tin, forming stannic chlorid but does not attack iron.

In practicing this invention the tin scrap is placed in any suitable vessel, and dry chlorin is introduced into contact with the scrap. The chlorin attacks the tin, forming stannlc' chlorid, the reaction is attended by active generation of heat, and care must be taken to control the temperature and keep it suf ficiently low. A temperature at the walls of the vessel of below 100 degrees Fahrenheit (38 degrees C.) is preferable, but so long as the temperature does not rise so high as to make it im ossible to hold the hand a ainst the vesse (say 140 degrees Fahre eit,) the process can be successfully practiced. At these relatively low temperatures the iron is attacked only very sli htly (about tothe extent of its alloy with t e tin of the coating) while practically all of the tin is converted into stannic chlorid. If the temperature rises too high, the underlying iron alsois attacked, so that it is of great importance to prevent any serious rise of temperature. The temperature may be kept down either by cooling the vessel or by suflieiently limiting t 1e amount of chlorin which enters the vesse. The temperature should be maintained high enough to secure" a complete detinning.

As stannic chloi'id a boiling point of "(231. degrees F.) it

(SnCl is a ,liquid having 1 14 degrees Centigrade I at the surface of the scrap by the heat of the reaction, but in such case it is retained within the vessel, being condensed on reaching cooler portions of the scrap or on the Walls of the vessel. It may be collected by inclining the vessel to drain the liquid from the iron scrap which remains in the vessel. The tin chlorid is very pure, as the impurities of the iron either are not attacked, or if attacked by chlorin remain in the vessel, adhering to the iron, as the iron compounds (chiefly FeCh) do not form liquids like stannic chlorid, and are not soluble in SnCl The stannic chlorid may be variously utilized. In the form of a crystalline hydrated salt it is an important article of commerce. If desired, tin or any compound thereof ma be recovered or formed from the stannic ch orid by any suitable or known treatment or reaction.

We claim as our invention 1. The recovery of tin from tin scrap by treating the latter in a closed vessel with dry chlorin to form stannic chlorid, maintaining the temperature sufliciently high to effect complete detinning and controlling the temperature to keep it belowthat at which the iron is attacked. 2. The recovery of tin from tin scrap by treat'ng the latter in a closed vessel with dry chlorin to form stannic chlorid, and regulat- "ingthe. tem mission of 0 below that at which the iron is attacked.

3. The recovery of tin from tin scrap by treating the latter in a closed vessel with dry chlorin to form stannic chlorid, heating internally by the heat of reaction to a temperature sufiiciently high to effect complete detinning and controlling the temperature to kee it below that at which the iron is attac ed.

4. The recovery of tin from tin scrap by treating the latter in a closed vessel with dry chlorin to form 'stannic chlorid, heating internally by the heat of reaction to a temperature sufficiently hi h to effect complete detinning and contro ling the temperature'by limiting the admission of chlorin and by cooling the vessel, to keep the temperature below that at which the iron is attacked.

5. Therecovery of tin from tin scrap by treating the latter in a closed vessel with dry erature by limiting the admay be partlyvaporizedfchlorin to form stannic chlorid, controlling HOLCOMBS ROCK, VIRGINIA, ASSIGNORS, PRODUCTS COMPANY, OF NEW YORK, N. Y., A CORPORA- lorin, to keep the temperature the temperature to keep it high enough to signed oui' names in the p'iesenee of two suh effect'compltle detiililning but l w enou h,t0 scribing witnesses.

revent ettac ing is e iron an to con ense Evithin the vessel such of the stennic chlorid 5 gi gfi 5 as is vaporized, and draining the liquid stan-' nic chlorid' from the residue of iron scrap Witnesses: within the vessel. GEd.- T.- LANCASTER, In Witness Whereofl we have hereunto JNo. B.- HUFFARD. 

